Work holder mechanism for machine tools



B. P. SCHILTZ WORK HOLDER MECHANISM FOR MACHINE TOOLS Aug. 16, 1949.

Filed Sept. 27, 1945 5 Shee ts-Sheet 1 TNVENTQH Bernar d IQ vSChiH') ,WWK/Vv% B. P. SCHILTZ 2,479,026

Aug. 16, 1949.

Filed Sept. 27, 1945 -r-ro a a Aug. 16, 1949. P, sc z 2,479,026

WORK HOLDER MECHANISM FOR MACHINE TOOLS I 5 Sheets-Sheet 3 Filed Sept. 2'7, 1945 NVENTO O I I I O l Pram: v

Patented Aug. 16, 1949 I f onnnotnmMEonAms 'rooLs:

Bernard P: Schiltz, Cleveland -Qhiq assignon't e I The. Foete-liun .G mpa y; ,Qlcwelamt Ohio a eerporat en ail-0 2. 1 1

erzpl cati nseptem 2'1, 1945, Serial?N0;--618;92z:.

'Ijhe present invention pertains to work holder mechanisms for machine tools andmore particularly to such mechanisms in which the work is automatically clamped, and 'unclamped in the course of'mqvement of the holder through themachine. r r

one Object .of the invention is to provide a mechanism of the class'indicatedix pwhioh safetymeans is provided-for automatically arrestingmqtion of theholder in the event of failure of e.cl mp'aq uating'm h n sm J More particularl itijs an object; to provide uq a. m chanism m yinee hammer m terpere in sucqessi mpin de ces oe h r w hm ns for automa ic lly r est ng. ur herjbp at o f m chine in the eventqt a failure of thehammer cam to elject proper operation of oneofthe devices:

A AQthQI Qblfipifi g mqvidemeans for prevent f ing; breakage of the hammercam or associated; elements in a mechanism of the class indicated when the motionof as for example uponan inadvertent reversal incidentto plugging an electric drive motor-for the work holder. v Furtherobj'ects and advantages efthe inventien will become apparentas 'the followlng deones. of a; series of work-f the work holder is reversed; a

scriptionj proceeds, taken in connection with the accompanying drawings; in which: v

Figure 1 is'aside elevationofa continuous tjrpe breaching machine embodying the present. inven-i than; 'aportion: of the housing and. bed structure being broken away to expose the interiorlylocated parts.- Fig. '2; is an. enlarged fragmentary plan. viewof: theiientrance or. rightethand portion of the ma-. chine showninliig; 1. v lite; :31 teen 1 enlarged: detail view? partially in. section. along the'linerhfi in Fig; 4 showing the: hammer-1 cam and associated;parts includedthe machine of Fig-.-, 1*. I r

The; 4, isf an enlargedtransverse. sectional. view taken substantially along the line 4- 4. in Fig;

fie fills a: schematic: wir ng haez emz f' th lectrie en rols otthe machine! 7 7 While the inventien suseeptlble. of venues; modifications and alternative constructions, I' have. shown in the drawings; and will her in. describe in detail" the, preterredemhodiment, but" itis totbe understood tha'tJIc doinot. thereby intend togl-imilz the; invention; to; the specifiosform. dis-1 closed, but intend to.- cover all. modificationsanw alternative. constructions tatlingwithinzthe. spirit n s ope of zthe-vinventibmeas expressed. in the. apnended olaims. v

- '6 claims. (Cl. 959),

'.Be.e1:rme;,.mo1;e particnlar y e h r win s,

the/.1 ntionlhas been illustratedtherein; as; em-v bedled ominuoes' vne' c ng machin since-the. nee ntr iv nti n ha prmarny i0 withthewprki-holder mechanism nc rpo ted. in the-machine simply a brief; outline; of the ma chine-structure aseawhele m'll-sufiice. As. shown, the mach-weds provided with a hollowbase. I10, supported h legs 1, (Fig: 1 Sectional broaches' I Late. ear ri -.by. abridge .43 mountedon the bedv intermediate its endsandconstituteinefiect the; .12. well l a. M 1391? hm which Successive.- werlmieces are. passed, Sheet metal covers. or ousin e- 15 max pot l neoithe mac ine,

workpieces. such. asindicatedat W (Fig. 1),,

are received, in a, series of; work holdersdesignated 1 generally L6 and areiearriedby the latter. be-

heath the. breaches. ton-surfaces. o; the; workpieces, machining the same'in, the manner customary in breaching. The work holders l6 aremounted betweena pair of...en1ese I]- trained ever sprockets, l8 arnedon shaftsv La J'journaledn n. opposite ends otthe QdLUL c eer; thelshattjs la is. driven by a. su ta leielectric drive. motor (not shown in:v Figbl t in icfitteiat 21L inthewiring diagram of; I

n h new- M men ion. of he ma hine th work. holders; ljij "are. advanced continuously" through their... endless path. The operator places the worljgnieceswin.successive ones of'the holders at the.ri'ght.,hand r entrance end of the ma-. chine. as viewed. in. El'ggj I. As. th holders ap- Preach the. tunnel in which the broaches I2; are. l cated, sultabIe clamping devices incorporated in; each of, the holdersareautomatic ally actuated fw lamn dwm itien. After lde me e. fromthe their clamping. devices areautomaticallx unclaimed; and. the, finished workpiece; may be removed;

Each. work: holder; l6. includes-a clampin devise compriseiofaeflxedljhw 2;! and a movable law 2- fi ehfixediaw s; rigid; h a e 1 plate.zihavingpinsjfigmigs,.Ziand 4) protrudingaterally thenef Qmandn which are ipurnaledappropriate; ones of; the. linlfss. 25; which make up the, chainsjl, 'lll'lelmovable. jaws .2 2. are fashioned imthe iblni .ot blpclrsreceived nl ngi i e rae ending ui ewa fiio the pstand-e ing forward portions 23 0f the base. plates 23... Guides, Tille- (Flig n carried by suitable. trans.- verse; webbing; I 0? illtheabfi d tlL-slidably receive. theibee nleteen hew-we Q the r. ra l :55 beneethzthehm ehesi 1 I 7 he provided toenclose. the end 2180. thalhtheilatter shear the.v

Each movable jaw 22 is equipped with a coacting actuator bar 21 (Fig. 2) which is movable endwise to cam the jaw into and out of clamping position. Such actuator bars 21 are slidable endwise in alined transverse holes 28 in the upstanding portions 23 of the base and also pass through generally centrally located transverse apertures 29 in the movable jaws 22. The leading and trailing edges of the bars 21 are relieved to form sloping surfaces 30 arranged to coact with complementally shaped PI'OtIUSiOIlSz'Bl on the inner side walls of the apertures 29 in the mov-v able jaws. The slope of the surfaces 30 is such that, upon an endwise movementof on of the actuator bars in a downward direction'as viewed in Fig. 2, the cooperating jaw 22 is cammed or wedged into clamping position against-"the work.-

end of the bar and finally drops off of the same into the position shown in full lines in Fig. 3.

' As an incident to such drop, the compressed piece W, whereas upon movement of the actuator bar in the opposite direction the movable jaw is withdrawn into unclamped position.

A hammer cam 32 (Figs. 2, 3 and 4) is employed for driving successive ones of the actuator bars 21 endwise as they are presented to it and in a direction to effect clamping of the work. In the present instance, the hammer cam 32 is fashioned in the form of an elongated arm pivoted on a pin 33 alongside the path of travel of the work holders to swing toward and from the latter. A spring 34 (Fig. 3) yieldably urges the hammer cam into position to intercept successive ones of the actuator bars 21. This spring is shown as a helical compression spring located in a tubular housing 35 having an adjusting plug 36 threaded in its outer end and a hollow plunger 31 slidably received in the inner end. The nose of this plunger bears against the outer side of a dog 39 carried on the end portion of the hammer cam and thus urges the latter to swing toward the v work holders with a force which may be varied by threading the adjusting plug 36 in or out. A stop 32 limits the swing of the hammer cam '32 inward toward the work holders.

The outer end portion of the hammer cam 32 is transversely apertured, as indicated at 38 in Fig. 3, to receive the dog 39 mentioned above. Such dog is pivoted within the aperture on a pin 40, the

pressed plunger31. The dimensions of the ape'ra ture 38 are such as to afiord clearance for the dog 39 to swing counterclockwise (as viewed in Fig. 3) away from the abutment 4| and when so swung the nose of the dog is withdrawn within the aperture 38. The element 39 thus constitutes a one-Way dog. Normally, the spring pressed plunger 31 holds the dog 39 in the out-thrust position shown in Fig. 3, a location in which the protruding nose of the dog constitutes a dropofi on the hammer cam and over which the ends of the bars 21 ride.

The ends of the actuator bars 21 are sloped rearwardly, as indicated at 21, complementally to the slope of the leading edge 32 of the hammercam when it occupies its unstressed position indicated in broken lines in' Fig. 3. It will be observed that the protruding nose portion of the dog 39 is also relieved or sloped as indicated at 3% to present a surface alined with the edge 32 of the hammer cam when the dog is in its fully projected position.

As each successive actuator bar 21 comes into contact with the hammer cam 32, its end portion 21 slides progressively along the edge (12 of the hammer cam, thrusting the latter outward from spring 34 drives the hammer cam 32 against the end of the actuator bar, causing a sharp blow to be delivered to the latter. The actuator bar 21 is thus driven endwise still further and completes the wedging of the cooperating movable clamp jaw 22 into clamping position.

In the event that one of the actuator bars 21 should stick or for any reason offer more than normal resistance to-movement, it would, without else, simply shoulder the hammer cam 32 aside a greater distance than normal and continue on without clamping the work. In accordance with one aspect of the present invention,

provision is made for automatically arresting further motion of the work holder IS in the event of such improper operation. For that purpose, a plunger 42 (Fig. 3) is arranged to slide endwise within a housing 42a at the outer side of the hammer cam 32. A compression spring 42b urges the plunger 42 toward the hammer cam, the plunger being located so that it remains clear of the hammer cam during normal movement of the latter. In the event the actuator bar 21 fails to shift, the hammer cam is, however, thrust outward a greater than normal distance and thus contacts the plunger 42, shoving it outward. Such movement of the plunger 42 causes its outer end portion to push downward the actuating button 43 of a switch located within a housing 44, the switch being designated as 45 in the wiring diagram'of Fig. 5. A resultant opening of the switch serves to stop the drive motor 20, as will hereinafter appear in further detail in connection with the description of the control circuits.

As a further safety measure to insure proper location of the workpieces W in the holders l5 prior to the presentation of the workpieces to the broaches l2, provision is also made for automatically stopping the holder drive motor 20' whenever one of the workpieces protrudes too far upward out of the holder. For that purpose a flap or shield 46 (Figs. 1 and 4) is mounted on a pivot shaft 41 at the entrance end-of the tunnel.

A tension spring 48 connected to an eccentric lug 49 on an arm 50 fixed to the end of the shaft 41 normally holds the shield 46 yieldably in vertical position, the arm being pressed against a switch operating button 5|. In the event that a workpiece protrudes too far above the holder it strikes the shield 46, swinging the latter inward of the tunnel, so that a cam surface 50 on the arm 50 (see also Fig.2) depresses the actuating button 5| of a switch housed within the casing 52 argd designated as 53 in the wiring diagram of Fig.

At the exit end of the tunnel (left end as viewed in Fig. 1) is located a stationary cam 54 (see also Fig. 4) which abuts against successive ones of th actuator bars 21 and restores them to their initial or unclalmped position. The workpieces are thus freed from successive holders as they emerge from the broach. The cam 54 is, as

' shown, located on the side of the machine op- 5; posite' tha hammer: cam-Ahead? mam-be fomrok a simple; fixedi presenting: aifiace; inclined xii-relation,'01 travelrandi toi'thezadiacent inclinedtends'kb (see;

Rig: mxonzthe bars;

Retenring tozthe'control'fcircuit shown;

Fig; 5; ithwill "be notedi that a start;

switch 5551s *DEQYidfld as+ wells. as: a pair" of: pnsl re button switches; 56:, :51; These switchesamay'be locatedia't anys,convenieisit-point.v on theitmachina with: the:- stop: SWitGhGStlOBBIBEdt example; at

opposite endsi so: amt theimachinei can; be: read ly" stopped wherever" the operator- .masr be: Cur- I 7 rent: isisupplied 'forrthamotor 2i] fmomgthree: phase:

upply lines LLB-hand L3. c

start thamachinainicperatiom the-operator closest the: start 55cmomentariht. This pletes an: -energiaing eincnitiier the actuate.- ing windingiit ofi a demand contractor-by: connectipg'tha same across ;liness;-1f|l:, ..b2; throu h aw enders-t em! which is: connected to the latter;

line.- When the iorwatdcontactonis thus picked up;- it: closes; ibsAmElinrQ0 1 I34$$JE1 which-connect; th motor Zi t'a ross the su ply line 1 ionaima towar irec ion, atthezsametime. pens auie iaracontacts. El act-closes i aux'liary contacts; E3, Opening ofthe; contacts, thea iuss ea ircuit-to which; further eferen s made elaha f rw rai' entactcr remain ener zed B though, start? closed only eementarilal V Y eathe ma teteeeie i ait i rware air -r he; the holde s a e eel-ranged; im ue:

a eeneath essiea. eaeatht be at er' et .H. ewed n s. Aah .issive ethhc derme .MFQLABQW" h 9 r ehthaaas rce se i' ir t a mach ne ra dress at t 'Iqle ls wqrkeieceiate "ihereat erthe-haeiaies cam 32 engages the work holder's actuator bar 21 and thrusts it inward to close the clamping jaw-*Zljfinally drivns; he her horse wi h their hammer 2. w. all as previously detailed. As the-workholders: emerge from the tunnel after completion of the broaching, theopeni-ng cam- 54 shoves the actuator bars; 21 back to openweach work holgegs lemriaaes ce, A i ene ia erstaii at ill at itae m mas can th e hit out lamped finis ed. wqr seieq ather m a ma e is talk mm a receptacl he b nea h: he' e th nas kst i d ires-i;

In the event that the hammer cam 32 fails to move one of the actuating bars 21 fully into the latter so that the other safety switch 53 is opened. Opening of either of the safety switches 45 or 53 or the opening of either of the stop switches 56 or 51, causes the drive motor 20 to be plugged to an immediate stop. It will be noted that all four of the switches 45, 53, 56 and 51 are connected in series so that the opening of any one of them has the same effect on the circuit.

As to the stopping operation, it will be noted that opening of any one of the series of switches 45, 53, 56 or 51 drops out the forward contactor so that its auxiliary contacts F2 reclose. This completes an energizing circuit between 4 whereasare holdin on a ts hunt withtne; fstart: witches-Sc;

ei qeeners zed in stopped pfls tion. Beeauseci' mal ad jgtstrnentfiof thekpiuggi i SWfl'LGhZ onfiorsctlitem easons-r i m mes ha' se s: in: c t um lci icver, that the motor: 2 war actuallyrererea an slea t. for ew yo zu ion z-z onset the. actuatorbar zit-to passthahammem cam. may be moy d ack ntc; :contactwitli -the-a at r -t-the dr p-ctr: shoulder on theIham-meis" cam were formed. by a rigid projection, breakagwwould ensue; littoprevent suchibreakagetha-t the dropeofi shoulder in; the present-.rinstancey; defined thefdog it previously described; This being acne-.way do iifi the end-or an actuators-has: is. reversed; into? contact.- wi-th: it,: the? bar" will pl yrswing therdcgcounterclockwise; (as viewed -i sc' hatsthe;b.arr2;l canipass freelyaia tn out damage. I; clai;

asmyinventiom;

1;. .-In-a machine tool, the'combmationrot der hwiimifid fmi K movement in a confinedt d havingiavciampingide ice:thereomipnwen' na-fohmoaingsaidholder; actuating said clam ing device *includin ra pair-r r JPQSWQIB; i ercept. the: first asatha; s asr- -"eereaaione its nathatboth 'QIf'Satd meanders being shiitable transversely of said path; thfir-a h taid me-m mbe serv ng o; actuatesaid tica. m yieldabi r etainins aia o her member; p0 'tion inwhich;saiglionezmenlb ide-ea itv assea sa aiei abie me ins ir s ci -eh c -mess ah o ercomathe s stance V,tte 'saieienememh ra actuate i sa the amount, whereby furth automatically arrested in the event said one member fails to shift for actuation of said clamping device and instead shoulders said other member aside as it passes the same.

2. In a machin tool, the combination of'a work holder mounted for movement in a confined path and having a clamping device thereon, power actuated means for moving said holder, actuating means for said clamping device includin a movable member carried by said holder and a coacting cam movably mounted alongside the path of such holder in position to intercept said movable member as the holder moves along its path, means for yieldably retaining said cam in a position in which said movable member rides over it as the member passes, said yieldable means being strong enough to overcome the normal resistance to shift of said movable member and thereby effect a shift of the latter to actuate said clamping device, and safety means for stopping said power actuated 75 means in response to a retraction motion of said ersing contactonso; that the motel? In. such caseathe lasti cam .in excess of a predetermined amount, whereby further travel of said holder is automatically arrested in the event said movable member fails to shift for actuation of said clamping device and instead shoulders said cam aside as it passes the same.

:3. In a machine tool, the combination of a work holder mounted for movement in aconflned path and having a clamping device thereon, power' actuated means for moving said holder, a hammer cam movably mounted alongside the path of said holder, an actuating member for said clamping device movably mounted on said holder and presenting means for loading and firing said hammer cam as the holder passes the same, said member being arranged for movement under the impact of said hammer cam upon firing of the latter, a safety switch for stopping said power actuated means, and a movable operating member for said safety'switch mounted adjacent said hammer cam, said operating member being adapted to trip said safety switch in response to a loading motion of said hammer cam in excess of a predetermined amount.

4, In a machine tool, the combination of a work holder mounted for movement in a confined path and having a clamping device thereon, reversible electric drive motor for moving said holder, a hammer cam pivotally mounted alongside the path of said holder and yieldingly urged toward the same, an actuating member for said clamping device movably mounted on said holder and projecting outward toward said hammer cam, a one-way dog mounted on said hammer cam and defining an abrupt drop-off shoulder presented to said actuating member as the latter underrides said hammer cam, said dog being mounted to swing freely clear of said member in the event of a reversal of the latter by said holder, and safety means for plugging said motor in response to movement of said hammer cam outward away from said holder in excess of a predetermined amount.

5. In a machine tool, the combination of a work holder having clamping jaws and an actuator bar slidable endwise for moving such jaws into and out of clamping position, means including a reversible electric drive motor for moving said holder through a confined path inwhich said actuator bar lies transverse to the direction of'movement, a hammer cam mounted alongside said path for movement toward and from the adjacent end of said actuator bar as the latter passes, a spring yieldably urging said cam into a position in which it intercepts the end of said bar as said holder advances, a dog pivoted on the active end of said hammer cam and spring urged against a fixed stop on the latter which locates said dog in position to project outward toward the path of said bar, said bar and cam having coacting surfaces thereon for camming said hammer cam back against the urging of said first mentioned spring and thereafter abruptly releasing the same for application of a hammer blow to said bar to drive the latter endwise as said bar rides 011 of said dog, and means for plugging said drive motor in response to camming of said hammer cam outward beyond a predetermined fixed distance, the pivotal mounting of said dog permitting said holder to reverse its motion-without breakage of said hammer cam and bar.

6. In a machine tool, the combination of a plurality of work holders each having a clamping mechanism, power actuated means for moving said holders in succession along a fixed path, a hammer cam mounted for movement toward and away from said path for actuating said clamping mechanisms one after another as the respective work holders pass such hammer cam, a one-way dog pivoted on said hammer cam for movement between an out-thrust position and a withdrawn position, said dog being adapted when in the out-thrust position to intercept a coacting portion of each successive clamping mechanism, an abutment on said hammer cam for defining the out-thrust position of said dog, and yieldable means effective during normal movement of said holders for maintaining said dog against said abutment and in said out-thrust position, said yieldable means being adapted upon reverse movement of said holders to permit free pivoting of said dog away from said abutment and toward said withdrawnposition.

BERNARD P. SCHILTZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,835,591 Bullard Dec. 8, 1931 1,939,038 Bower Dec. 12, 1933 1,979,478 Leland Nov. 6, 1934 2,025,070 Nygren Dec. 24, 1935 2,063,955 Schiltz Dec. 15, 1936 

